Various communication devices utilize both a speaker and a microphone. The conventional telephone type "handset, " which is used both for wire-line telephone communication and two-way radio communication, includes a housing having a speaker at one end and a microphone at the other. The speaker and microphone are positioned so that the handset can be held with the speaker adjacent to the user's ear and the microphone in proximity to the user's mouth. Such handsets are used both for full duplex communication, such as a telephone where audio can be produced at the speaker at the same time the user is articulating sound into the microphone. This is conventional in both land line telephone systems and some two-way radio systems. Such a handset can also be used in what is known as half-duplex radio communication, in which voice signals are alternatively transmitted or received. When used in such a configuration, either a push-to-talk switch (PTT) is provided or else a voice-actuated transmit circuit (VOX) can be utilized. Portable, two-way radio transceivers, such as those used in the land mobile radio service, typically include both a microphone and speaker in the housing. While early two-way radio transceivers had the speaker and the microphone configured to permit their use in a manner similar to a telephone handset, most two-way radio transceivers today have the speaker and microphone in relatively close proximity since these devices are typically half duplex and are not capable of simultaneous transmission and reception of signals. This arrangement will be referred to as the speaker-microphone configuration.
Speaker-microphones are devices typically used with radios such as portable or mobile radios, to enable the user to hold the microphone unit, which is connected by a cable to the radio. When used in conjunction with a portable two-way radio, this permits the radio to remain as, for example, clipped to the user's belt, while providing both the audio output and the microphone audio input to the remote unit which the user can position as desired.
Small, foldable radio telephones units, such as the MICROTACO.RTM. cellular telephone manufactured by Motorola, Inc., and radios for use in the new CT-2 time division duplex radio system are foldable to provide a compact housing. When the user desires to place or receive a telephone call, the unit is unfolded to permit its use as a handset with the speaker and microphone disposed in positions relatively close to the user's ear and mouth respectively. All these known devices are relatively inflexible in that their use is essentially limited to the predetermined configuration either as a telephone-type handset or as a speaker-microphone configuration.